Force equalization with non-responsive sensor detection

ABSTRACT

In an embodiment, a method of monitoring force equalization (FEQ) sensors on a vehicle utilizing redundant actuation systems for one or more control surfaces includes determining, via a force sensor, a first measured force applied by a first actuation system in relation to a control surface, where the control surface is redundantly serviced by a plurality of actuation systems that include the first actuation system. The method also includes updating a measured-force time series for the first actuation system with the first measured force. The method also includes determining variation in at least a portion of the measured-force time series responsive to the updating. The method also includes identifying a first static condition in the measured-force time series in response to a determination that the variation in the measured-force time series is no greater than a minimum amount of variation.

BACKGROUND Technical Field

The present disclosure relates generally to vehicle monitoring and moreparticularly, but not by way of limitation, to systems and methods fordetecting and managing force cycles in force equalization systems.

History of Related Art

Redundant actuators are often used in vehicles such as aircraft toimprove, for example, safety and fault tolerance. Although thisredundancy can be advantageous, it can also create new problems relatedto uneven use of actuators and resultant fatigue. Many flight-controlsystems employ force-equalization algorithms to balance force exertionamong redundant actuators.

SUMMARY

A system of one or more computers can be configured to performparticular operations or actions by virtue of having software, firmware,hardware, or a combination of them installed on the system that inoperation causes or cause the system to perform the actions. One or morecomputer programs can be configured to perform particular operations oractions by virtue of including instructions that, when executed by dataprocessing apparatus, cause the apparatus to perform the actions.

In an embodiment, one general aspect includes a method of monitoringforce equalization (FEQ) sensors on a vehicle utilizing redundantactuation systems for one or more control surfaces. The method includesdetermining, via a force sensor, a first measured force applied by afirst actuation system in relation to a control surface, where thecontrol surface is redundantly serviced by a plurality of actuationsystems that include the first actuation system. The method alsoincludes updating a measured-force time series for the first actuationsystem with the first measured force. The method also includesdetermining variation in at least a portion of the measured-force timeseries responsive to the updating. The method also includes identifyinga first static condition in the measured-force time series in responseto a determination that the variation in the measured-force time seriesis no greater than a minimum amount of variation. Other embodiments ofthis aspect include corresponding computer systems, apparatus, andcomputer programs recorded on one or more computer storage devices, eachconfigured to perform the actions of the methods.

In an embodiment, another general aspect includes a vehicle computersystem that includes a processor and memory. The processor and memory incombination are operable to perform a method of managing forceequalization (FEQ). The method includes determining, via a force sensor,a first measured force applied by a first actuation system in relationto a control surface, where the control surface is redundantly servicedby a plurality of actuation systems that include the first actuationsystem. The method also includes updating a measured-force time seriesfor the first actuation system with the first measured force. The methodalso includes determining variation in at least a portion of themeasured-force time series responsive to the updating. The method alsoincludes identifying a first static condition in the measured-force timeseries in response to a determination that the variation in themeasured-force time series is no greater than a minimum amount ofvariation.

In an embodiment, another general aspect includes a computer-programproduct that further includes a non-transitory computer-usable mediumhaving computer-readable program code embodied therein. Thecomputer-program product is adapted to be executed to implement a methodof managing force equalization (FEQ). The method includes determining,via a force sensor, a first measured force applied by a first actuationsystem in relation to a control surface, where the control surface isredundantly serviced by a plurality of actuation systems that includethe first actuation system. The method also includes updating ameasured-force time series for the first actuation system with the firstmeasured force. The method also includes determining variation in atleast a portion of the measured-force time series responsive to theupdating. The method also includes identifying a first static conditionin the measured-force time series in response to a determination thatthe variation in the measured-force time series is no greater than aminimum amount of variation.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the method and apparatus of the presentdisclosure may be obtained by reference to the following DetailedDescription when taken in conjunction with the accompanying Drawingswherein:

FIG. 1 illustrates an aircraft;

FIG. 2 illustrates an example of a force equalization (FEQ) system;

FIG. 3 illustrates an example of an FEQ system;

FIG. 4 illustrates an example of an FEQ module;

FIG. 5 illustrates an example of a process for improving fault tolerancein FEQ systems by detecting non-responsive force sensors; and

FIG. 6 illustrates an example of a computer system.

DETAILED DESCRIPTION

While the making and using of various embodiments of the presentdisclosure are discussed in detail below, it should be appreciated thatthe present disclosure provides many applicable inventive concepts,which can be embodied in a wide variety of specific contexts. Thespecific embodiments discussed herein are merely illustrative and do notdelimit the scope of the present disclosure. In the interest of clarity,not all features of an actual implementation may be described in thepresent disclosure. It will of course be appreciated that in thedevelopment of any such actual embodiment, numerousimplementation-specific decisions must be made to achieve thedeveloper's specific goals, such as compliance with system-related andbusiness-related constraints, which will vary from one implementation toanother. Moreover, it will be appreciated that such a development effortmight be complex and time-consuming but would be a routine undertakingfor those of ordinary skill in the art having the benefit of thisdisclosure.

In the specification, reference may be made to the spatial relationshipsbetween various components and to the spatial orientation of variousaspects of components as the devices are depicted in the attacheddrawings. However, as will be recognized by those skilled in the artafter a complete reading of the present disclosure, the devices,members, apparatuses, and the like described herein may be positioned inany desired orientation. Thus, the use of terms such as “above,”“below,” “upper,” “lower” or other like terms to describe a spatialrelationship between various components or to describe the spatialorientation of aspects of such components should be understood todescribe a relative relationship between the components or a spatialorientation of aspects of such components, respectively, as the devicedescribed herein may be oriented in any desired direction. In addition,as used herein, the term “coupled” may include direct or indirectcoupling by any means, including moving and/or non-moving mechanicalconnections.

The present disclosure describes examples of improving the faulttolerance of force equalization (FEQ) in vehicles that utilize redundantactuation systems for control surfaces. For purposes of this patentapplication, the term “vehicle” includes, but is not limited to, land,water and air-based vessels or vehicles including, but not limited to,water vessels, aircraft, and land-based vehicles such as automobiles andtrains. For purposes of illustration, examples will be periodicallydescribed herein relative to aircraft. It should be appreciated,however, that the principles described herein are not limited toaircraft and can similarly be applied to any other type of vehicleutilizing redundant actuation systems for control surfaces.

FIG. 1 illustrates an aircraft 100 according to one example embodiment.For illustrative purposes, the aircraft 100 is shown to be a rotorcraft.Aircraft 100 features a rotor system 110, blades 120, a fuselage 130, alanding gear 140, and an empennage 150. Rotor system 110 may rotateblades 120. Rotor system 110 may include a control system forselectively controlling the pitch of each blade 120 in order toselectively control direction, thrust, and lift of aircraft 100.Fuselage 130 represents the body of aircraft 100 and may be coupled torotor system 110 such that rotor system 110 and blades 120 may movefuselage 130 through the air. Landing gear 140 supports aircraft 100when aircraft 100 is landing and/or when aircraft 100 is at rest on theground. Empennage 150 represents the tail section of the aircraft. Apilot may manipulate pilot flight controls in order to achievecontrolled aerodynamic flight. Teachings of certain embodiments relatingto rotor systems described herein may apply to rotor system 110 and/orother rotor systems, such as other tilt rotor and helicopter rotorsystems. It should also be appreciated that teachings from aircraft 100may apply to aircraft other than rotorcraft, such as airplanes andunmanned aircraft, to name a few examples. Similarly, as mentionedpreviously, the teachings from aircraft 100 can also be applied to othertypes of vehicles.

An FEQ system 180 is schematically shown in fuselage 130, but it shouldbe appreciated that the FEQ system 180 may take a number of forms andhave its components distributed throughout a variety of locations withinaircraft 100. The FEQ system 180 can function, at least in part, as avehicle monitoring system and, in a typical embodiment, is configured tocontrol and communicate with various systems within aircraft 100. TheFEQ system 180 can include, for example, one or more flight controlcomputers and multiple actuation systems that redundantly service one ormore flight control surfaces, where the one or more flight controlsurfaces change the flight characteristics of the aircraft such as, forexample, the positions of blades 120 of FIG. 1.

In certain embodiments, the FEQ system 180 can endeavor to balance loadamong the multiple actuators. Further, in various embodiments, operationof multiple actuators on a control surface can introduce force fight,where instead of equally sharing load the actuators behave unequally orin opposition to each other. In certain embodiments, the FEQ system 180can monitor the way in which FEQ is applied therein and configurablyexecute FEQ failure logic in defined situations. The FEQ failure logiccan include, for example, disabling an actuation system responsible forcreating force fight.

FIG. 2 illustrates an example of an FEQ system 280 that can serve, forexample, as the FEQ system 180 of FIG. 1. The FEQ system 280 includes aflight control computer (FCC) 282 in communication with actuationsystems 284A, 284B, and 284C (collectively, redundant actuation systems284). The redundant actuation systems 284 redundantly service, andoperate on, a flight control surface 286.

The actuation systems 284A, 284B and 284C include actuators 288A, 288Band 288C (collectively, actuators 288), respectively, and force sensors290A, 290B and 290C (collectively, force sensors 290), respectively. Insome embodiments, the redundant actuation systems 284 can each representa single line-replaceable unit (LRU). In other embodiments, some or allcomponents of each of the redundant actuation systems 284 can representseparate LRUs.

The actuator 288A can be, for example, a hydraulic or pneumatic actuator(e.g., a piston or ram) operable to apply force to position the flightcontrol surface 286. The force sensor 290A can be, for example, a deltapressure sensor that detects force applied by the actuator 288A in theform of a pressure difference across the actuator 288A. In general, theactuators 288B and 288C can operate as described relative to theactuator 288A. The force sensors 290B and 290C can operate as describedrelative to the force sensor 290A, except that their force-sensingoperation occurs with respect to the actuators 288B and 288C,respectively.

In certain embodiments, the FCC 282 can include an FEQ module 283 thatbalances, between the redundant actuation systems 284, force applied tothe flight control surface 286. The FEQ module 283, via the forcesensors 290, can continuously or periodically receive a measured forceapplied by each of the actuators 288 in relation to the flight controlsurface 286. In addition, the FEQ module 283 can continuously orperiodically receive, or determine, a target force representing, forexample, a target force for each of the redundant actuation systems 284.In some embodiments, the target force can represent an aggregate valuedetermined from the measured force applied by each of the actuators 288.The aggregate value can be, for example, a mean, median, or otherstatistical value.

Based on the received and/or determined information, the FEQ module 283can continuously or periodically determine an FEQ command for each ofthe redundant actuation systems 284 and thereafter issue such commands.For any given actuator system of the redundant actuation systems 284,the FEQ command may represent a force adjustment in the form of reducedforce or increased force. In some cases, the FEQ command may indicate nochange in force. An example of the FEQ module 283 will be described withrespect to FIG. 4.

FIG. 3 illustrates an example of an FEQ system 380 in which multipleFCCs collaborate in providing positional control and FEQ functionalityfor a flight control surface 386. The FEQ system 380 can serve, forexample, as the FEQ system 180 of FIG. 1. The FEQ system 380 includesthree FCCs, namely, FCCs 382A, 382B and 382C (collectively, FCCs 382),three actuation systems, namely, actuation systems 384A, 384B and 384C(collectively, redundant actuation systems 384), and a flight controlsurface 386. In a typical embodiment, the flight control surface 386 isgenerally similar to the flight control surface 286 of FIG. 2 and can beoperated on by the redundant actuation systems 384.

The actuation systems 384A, 384B and 384C include actuators 388A, 388Band 388C (collectively, actuators 388), respectively, and force sensors390A, 390B and 390C (collectively, force sensors 390), respectively. Ingeneral, the redundant actuation systems 384, the actuators 388, and theforce sensors 390 can operate as described relative to the redundantactuation systems 284, the actuators 288, and the force sensors 290,respectively, of FIG. 2. In some embodiments, the actuators 388 canrelate to different controllable portions of a common actuationcomponent, such as a triplex actuator 392 in the illustrated embodiment.For example, in an embodiment, the triplex actuator 392 can includemultiple hydraulic cylinders and the actuators 388 can each correspondto a different hydraulic cylinder therein.

The FCCs 382A, 382B and 382C (collectively, FCCs 382) include FEQmodules 383A, 383B and 383C (collectively, FEQ modules 383),respectively. In general, the FCCs 382 and the FEQ modules 383 canoperate as described relative to the FCC 282 and the FEQ module 283,respectively, of FIG. 2. In the embodiment of FIG. 3, FEQ functionalityfor the flight control surface 386 is distributed among the FCCs 382such that the FCC 382A controls FEQ functionality for the actuationsystem 384A, the FCC 382B controls FEQ functionality for the actuationsystem 384B, and the FCC 382C controls FEQ functionality for theactuation system 384C. Stated somewhat differently, the FCCs 382A, 382Band 382B are responsible for determining and issuing FEQ commands forthe actuation systems 384A, 384B and 384C, respectively.

As illustrated, the FCCs 382 can intercommunicate, for example, via across-channel data link, to share data regarding the redundant actuationsystems 384. In this fashion, the FEQ modules 383 of each of the FCCs382 thereby have access to information related to measured force foreach of the redundant actuation systems 384, which information can beused to determine both a target force (e.g., a uniform target force)across the redundant actuation systems 384 and individual new FEQcommands for each of the redundant actuation systems 384. In addition,or alternatively, the FCCs 382 can intercommunicate to jointly establishthe target force and the FEQ commands, with each of the FCCs 382thereafter issuing such FEQ commands in the manner previously described.

It should be appreciated that FEQ functionality for a given controlsurface, such as the flight control surface 386, can be distributed toor among one, two, three, four, or any other suitable number of FCCs. Inaddition, for simplicity of illustration, the FEQ system 380 isdescribed relative to a single control surface, specifically, the flightcontrol surface 386. However, it should be appreciated that a given FCC,such as any of the FCCs 382, can control a set of redundant actuationsystems similar to the redundant actuation systems 384 for each of amultitude of control surfaces.

FIG. 4 illustrates an example of an FEQ module 483 that can correspond,for example, to any of the FEQ modules 283 and 383 of FIGS. 2 and 3,respectively. The FEQ module 483 includes an FEQ controller 492, anauthority monitor 494, and a force-sensor monitor 496. In theillustrated embodiment, the FEQ module 483 controls FEQ functionalityfor an actuation system 484 relative to a flight control surface 486.The actuation system 484 includes an actuator 488 and a force sensor490. Although only the actuation system 484 is illustrated in FIG. 4 forsimplicity, it should be appreciated that the flight control surface 486is assumed to be redundantly operated by multiple actuation systems insimilar fashion to the embodiments described relative to FIGS. 2-3.

The FEQ controller 492, via the force sensor 490, can continuously orperiodically receive a measured force applied by the actuation system484 as well as measured force applied by other actuation systemsinvolved in redundantly servicing the flight control surface 486. Inaddition, the FEQ controller 492 continuously or periodically receives,or determines, a target force for the actuation system 484. Based onthis information, the FEQ controller 492 can continuously orperiodically determine an FEQ command for the actuator 488 andthereafter issue such command. As described previously, the FEQ commandmay represent a force adjustment, for example, in the form of reducedforce or increased force. In some cases, the FEQ command may indicate nochange in force.

The authority monitor 494 is operable to monitor, for example, each FEQcommand issued by the FEQ controller 492, and to determine if the FEQmodule 483 has exceeded its FEQ authority. In various embodiments, FEQauthority can be defined using an authority threshold that is expressed,for example, in terms of inches of actuator or another suitable metric.In certain embodiments, if a given FEQ command from the FEQ controller492 instructs a force adjustment that is in excess of the authoritythreshold, the FEQ controller 492 may be determined to have exceeded itsFEQ authority, at which point the authority monitor 494 can cause FEQfailure logic to be executed. In many cases, a force adjustment inexcess of the authority threshold is indicative of a failure to balance,and hence a force fight. As part of executing the FEQ failure logic, theauthority monitor 494 can cause the actuation system 484 to be disabled,such that it no longer participates as a redundant actuator for theflight control surface 486. In some embodiments, executing the FEQfailure logic can result in FEQ being disabled for a given controlsurface. Other options for the FEQ failure logic will be apparent to oneskilled in the art after a detailed review of the present disclosure.

In various embodiments, the force-sensor monitor 496 can be used todetect and address other types of FEQ faults that manifest in a moresubtle fashion than in a command in excess of authority. Theforce-sensor monitor 496 can monitor measured force as it iscontinuously or periodically received, for example, from the forcesensor 490, and progressively build a measured-force time series for theactuation system 484. As the measured-force time series is updated, theforce-sensor monitor 496 can analyze variation in the measured-forcetime series in order to detect static conditions in the measured-forcetime series. The static condition can be configurably defined. Forexample, the static condition can be defined as no more than a minimumamount of variation over a configurable interval (e.g., variation ofless than 200 pound-force per square inch (PSI) over a five-minuteinterval). In response to identifying a static condition, theforce-sensor monitor 496 can test the force sensor 490, for example, bysending a command stimulus to at least the actuation system 484. Invarious embodiments, the force sensor 490 can be classified asnon-responsive if the command stimulus does not produce an expectedchange in measured force, at which point FEQ failure logic can betriggered. Example operation of the force-sensor monitor 496 will bedescribed in greater detail relative to FIG. 5.

FIG. 5 illustrates an example of a process 500 for improving faulttolerance in FEQ systems by monitoring force sensors. In a typicalembodiment, the process 500 can be executed with respect to a forcesensor of an actuation system. For illustrative purposes, the process500 will be described relative to the force sensor 490 of the actuationsystem 484. It should be appreciated, however, that the process 500 canbe executed in parallel for each of a plurality of force sensors thatmay be in use in a given FEQ system. In addition, although the process500 can be executed by any number of different components, to simplifydiscussion, the process 500 will be described as being performed by theforce-sensor monitor 496 of FIG. 4.

At block 502, the force-sensor monitor 496 determines, via the forcesensor 490, a measured force applied by the actuation system 484 inrelation to the flight control surface 486. As described relative toFIGS. 2-3, the flight control surface 486 can be redundantly served by aplurality of actuation systems, inclusive of the actuation system 484.In a typical embodiment, the force-sensor monitor 496 determines themeasured force on a continuous or periodic basis by receiving themeasured force from the force sensor 490.

At block 504, the force-sensor monitor 496 updates a measured-force timeseries for the force sensor 490 with the measured force determined atthe block 502. If the measured force received at the block 502represents the first such measured force, the block 502 can includecreating the measured-force time series. In various embodiments, theblock 504 can involve the force-sensor monitor 496 adding the measuredforce to a data structure representing the measured-force time series.

At block 506, the force-sensor monitor 496 determines variation in atleast a portion of the measured-force time series over an intervalthereof. For example, the force-sensor monitor 496 can determine adifference between a maximum and minimum value over an interval of themeasured-force time series. One skilled in the art will appreciate thatvariation can also be determined or measured in other ways withoutdeviating from the principles described herein.

At decision block 508, the force-sensor monitor 496 determines whether astatic condition exists in the measured-force time series. As describedpreviously, criteria for the existence of a static condition can beconfigurably defined. For example, the static condition can be definedas no more than a minimum amount of variation over a configurableinterval (e.g., variation of less than 200 PSI over a five-minuteinterval). In certain embodiments, the decision block 508 can involvecomparing, for example, a determined variation (e.g., a differencebetween maximum and minimum values) to the minimum amount of variation.According to this example, if the determined difference is no greaterthan the minimum of amount of variation, a static condition can bedetermined to exist. If the decision block 508 results in an affirmativedetermination, the process 500 proceeds to block 510. Otherwise, theprocess 500 returns to the block 502 and executes as describedpreviously.

At block 510, the force-sensor monitor 496 sends a command stimulus tothe actuation system 484. In a typical embodiment, the command stimulusinstructs the actuator 488 to move in a way that is expected to causethe force sensor 490 to produce a change in its measured-force data,such that the minimum amount of variation described above is exceeded.At block 512, the force-sensor monitor 496 determines new measured-forcedata. In various embodiments, the new measured-force data can includeone, two, three or any number of representative values from the forcesensor 490. In general, the new measured-force data is a sufficientnumber of values for determining whether a static condition exists afterthe command stimulus.

At decision block 514, the force-sensor monitor 496 determines whether astatic condition exists in the new measured-force data (i.e., after thecommand stimulus). A negative determination at the decision block 514generally means that the force sensor 490 is responsive. A positivedetermination, however, generally means that it is appropriate toclassify the force sensor 490 as non-responsive. If the decision block514 results in a negative determination, the force sensor 490 isclassified or treated as responsive and the process 500 returns to theblock 502 and executes as described previously. Otherwise, if thedecision block 514 results in a positive determination, the process 500proceeds to block 516, where the force sensor 490 is classified asnon-responsive.

At block 518, the force-sensor monitor 496 executes FEQ failure logic.In general, the FEQ failure logic can include any routine that attemptsto report, remediate, or somehow address the non-responsiveclassification of the force sensor 490. In some embodiments, the FEQfailure logic can proceed in a stepwise fashion, with progressively moresevere measures being taken in each iteration of the block 518. In someembodiments, execution of the FEQ failure logic results in disabling theactuation system 484, such that it is no longer involved in redundantlyservicing the flight control surface 486.

From block 518, the process 500 returns to the block 502 and executes asdescribed previously. In various embodiments, the process 500 cancontinue indefinitely, for example, until a conclusion of a mission ortrip, shutdown of the aircraft, termination by an administrator or user,or whenever other suitable stop criteria is satisfied. In addition, insome embodiments, execution of the FEQ failure logic can result intermination of the process 500.

For simplicity of description, the process 500 is described relative toa command stimulus that is sent to a single actuation system, namely,the actuation system 484, after a static condition thereof has beenidentified. In some embodiments, some or all of the process 500 can beperformed relative to all or any combination of the multiple actuationsystems involved in redundantly servicing the flight control surface486. For example, after a static condition has been identified relativeto the actuation system 484, blocks 510-518 can be performed in asequential pattern for each of the multiple actuation systems involvedin servicing the flight control surface 486 in an effort to determinewhether the static condition represents non-responsiveness. Othervariations will be apparent to one skilled in the art after a detailedreview of the present disclosure.

FIG. 6 illustrates an example of a computer system 600. In some cases,the computer system 600 can be representative of a computer such as, forexample, the FCC 282 of FIG. 2 and/or any of the FCCs 382 of FIG. 3. Thecomputer system 600 includes an application 622 operable to execute oncomputer resources 602. The application 622 can include, for example,logic for executing functionality of the FEQ module 283, any of the FEQmodules 383, the FEQ module 483, and/or a functionality of a componentof any of the foregoing. In particular embodiments, the computer system600 may perform one or more actions described or illustrated herein. Inparticular embodiments, one or more computer systems may providefunctionality described or illustrated herein. In particularembodiments, encoded software running on one or more computer systemsmay perform one or more actions described or illustrated herein orprovide functionality described or illustrated herein.

The components of the computer system 600 may include any suitablephysical form, configuration, number, type and/or layout. As an example,and not by way of limitation, the computer system 600 may include anembedded computer system, a system-on-chip (SOC), a single-boardcomputer system (SBC) (such as, for example, a computer-on-module (COM)or system-on-module (SOM)), a desktop computer system, a laptop ornotebook computer system, an interactive kiosk, a mainframe, a mesh ofcomputer systems, a mobile telephone, a personal digital assistant(PDA), a wearable or body-borne computer, a server, or a combination oftwo or more of these. Where appropriate, the computer system 600 mayinclude one or more computer systems; be unitary or distributed; spanmultiple locations; span multiple machines; or reside in a cloud, whichmay include one or more cloud components in one or more networks.

In the depicted embodiment, the computer system 600 includes a processor608, memory 620, storage 610, interface 606, and bus 604. Although aparticular computer system is depicted having a particular number ofparticular components in a particular arrangement, this disclosurecontemplates any suitable computer system having any suitable number ofany suitable components in any suitable arrangement.

Processor 608 may be a microprocessor, controller, or any other suitablecomputing device, resource, or combination of hardware, software and/orencoded logic operable to execute, either alone or in conjunction withother components, (e.g., memory 620), the application 622. Suchfunctionality may include providing various features discussed herein.In particular embodiments, processor 608 may include hardware forexecuting instructions, such as those making up the application 622. Asan example, and not by way of limitation, to execute instructions,processor 608 may retrieve (or fetch) instructions from an internalregister, an internal cache, memory 620, or storage 610; decode andexecute them; and then write one or more results to an internalregister, an internal cache, memory 620, or storage 610.

In particular embodiments, processor 608 may include one or moreinternal caches for data, instructions, or addresses. This disclosurecontemplates processor 608 including any suitable number of any suitableinternal caches, where appropriate. As an example, and not by way oflimitation, processor 608 may include one or more instruction caches,one or more data caches, and one or more translation lookaside buffers(TLBs). Instructions in the instruction caches may be copies ofinstructions in memory 620 or storage 610 and the instruction caches mayspeed up retrieval of those instructions by processor 608. Data in thedata caches may be copies of data in memory 620 or storage 610 forinstructions executing at processor 608 to operate on; the results ofprevious instructions executed at processor 608 for access by subsequentinstructions executing at processor 608, or for writing to memory 620,or storage 610; or other suitable data. The data caches may speed upread or write operations by processor 608. The TLBs may speed upvirtual-address translations for processor 608. In particularembodiments, processor 608 may include one or more internal registersfor data, instructions, or addresses. Depending on the embodiment,processor 608 may include any suitable number of any suitable internalregisters, where appropriate. Where appropriate, processor 608 mayinclude one or more arithmetic logic units (ALUs); be a multi-coreprocessor; include one or more processors 608; or any other suitableprocessor.

Memory 620 may be any form of volatile or non-volatile memory including,without limitation, magnetic media, optical media, random access memory(RAM), read-only memory (ROM), flash memory, removable media, or anyother suitable local or remote memory component or components. Inparticular embodiments, memory 620 may include random access memory(RAM). This RAM may be volatile memory, where appropriate. Whereappropriate, this RAM may be dynamic RAM (DRAM) or static RAM (SRAM).Moreover, where appropriate, this RAM may be single-ported ormulti-ported RAM, or any other suitable type of RAM or memory. Memory620 may include one or more memories 220, where appropriate. Memory 620may store any suitable data or information utilized by the computersystem 600, including software embedded in a computer readable medium,and/or encoded logic incorporated in hardware or otherwise stored (e.g.,firmware). In particular embodiments, memory 620 may include main memoryfor storing instructions for processor 608 to execute or data forprocessor 608 to operate on. In particular embodiments, one or morememory management units (MMUs) may reside between processor 608 andmemory 620 and facilitate accesses to memory 620 requested by processor608.

As an example, and not by way of limitation, the computer system 600 mayload instructions from storage 610 or another source (such as, forexample, another computer system) to memory 620. Processor 608 may thenload the instructions from memory 620 to an internal register orinternal cache. To execute the instructions, processor 608 may retrievethe instructions from the internal register or internal cache and decodethem. During or after execution of the instructions, processor 608 maywrite one or more results (which may be intermediate or final results)to the internal register or internal cache. Processor 608 may then writeone or more of those results to memory 620. In particular embodiments,processor 608 may execute only instructions in one or more internalregisters or internal caches or in memory 620 (as opposed to storage 610or elsewhere) and may operate only on data in one or more internalregisters or internal caches or in memory 620 (as opposed to storage 610or elsewhere).

In particular embodiments, storage 610 may include mass storage for dataor instructions. For example, in various embodiments, storage 610 canstore all or a portion of the contents of the data store(s) 208 of FIG.2. As an example, and not by way of limitation, storage 610 may includea hard disk drive (HDD), a floppy disk drive, flash memory, an opticaldisc, a magneto-optical disc, magnetic tape, or a Universal Serial Bus(USB) drive or a combination of two or more of these. Storage 610 mayinclude removable or non-removable (or fixed) media, where appropriate.Storage 610 may be internal or external to the computer system 600,where appropriate. In particular embodiments, storage 610 may benon-volatile, solid-state memory. In particular embodiments, storage 610may include read-only memory (ROM). Where appropriate, this ROM may bemask-programmed ROM, programmable ROM (PROM), erasable PROM (EPROM),electrically erasable PROM (EEPROM), electrically alterable ROM (EAROM),or flash memory or a combination of two or more of these. Storage 610may take any suitable physical form and may include any suitable numberor type of storage. Storage 610 may include one or more storage controlunits facilitating communication between processor 608 and storage 610,where appropriate.

In particular embodiments, interface 606 may include hardware, encodedsoftware, or both providing one or more interfaces for communication(such as, for example, packet-based communication) among any networks,any network devices, and/or any other computer systems. As an example,and not by way of limitation, communication interface 606 may include anetwork interface controller (NIC) or network adapter for communicatingwith an Ethernet or other wire-based network and/or a wireless NIC(WNIC) or wireless adapter for communicating with a wireless network.

Depending on the embodiment, interface 606 may be any type of interfacesuitable for any type of network for which computer system 600 is used.As an example, and not by way of limitation, computer system 600 caninclude (or communicate with) an ad-hoc network, a personal area network(PAN), a local area network (LAN), a wide area network (WAN), ametropolitan area network (MAN), or one or more portions of the Internetor a combination of two or more of these. One or more portions of one ormore of these networks may be wired or wireless. As an example, computersystem 600 can include (or communicate with) a wireless PAN (WPAN) (suchas, for example, a BLUETOOTH WPAN), a WI-FI network, a WI-MAX network,an LTE network, an LTE-A network, a cellular telephone network (such as,for example, a Global System for Mobile Communications (GSM) network),or any other suitable wireless network or a combination of two or moreof these. The computer system 600 may include any suitable interface 606for any one or more of these networks, where appropriate.

In some embodiments, interface 606 may include one or more interfacesfor one or more I/O devices. One or more of these I/O devices may enablecommunication between a person and the computer system 600. As anexample, and not by way of limitation, an I/O device may include akeyboard, keypad, microphone, monitor, mouse, printer, scanner, speaker,still camera, stylus, tablet, touchscreen, trackball, video camera,another suitable I/O device or a combination of two or more of these. AnI/O device may include one or more sensors. Particular embodiments mayinclude any suitable type and/or number of I/O devices and any suitabletype and/or number of interfaces 606 for them. Where appropriate,interface 606 may include one or more drivers enabling processor 608 todrive one or more of these I/O devices. Interface 606 may include one ormore interfaces 606, where appropriate.

Bus 604 may include any combination of hardware, software embedded in acomputer readable medium, and/or encoded logic incorporated in hardwareor otherwise stored (e.g., firmware) to couple components of thecomputer system 600 to each other. As an example, and not by way oflimitation, bus 604 may include an Accelerated Graphics Port (AGP) orother graphics bus, an Enhanced Industry Standard Architecture (EISA)bus, a front-side bus (FSB), a HYPERTRANSPORT (HT) interconnect, anIndustry Standard Architecture (ISA) bus, an INFINIBAND interconnect, alow-pin-count (LPC) bus, a memory bus, a Micro Channel Architecture(MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express(PCI-X) bus, a serial advanced technology attachment (SATA) bus, a VideoElectronics Standards Association local (VLB) bus, or any other suitablebus or a combination of two or more of these. Bus 604 may include anynumber, type, and/or configuration of buses 604, where appropriate. Inparticular embodiments, one or more buses 604 (which may each include anaddress bus and a data bus) may couple processor 608 to memory 620. Bus604 may include one or more memory buses.

Herein, reference to a computer-readable storage medium encompasses oneor more tangible computer-readable storage media possessing structures.As an example, and not by way of limitation, a computer-readable storagemedium may include a semiconductor-based or other integrated circuit(IC) (such, as for example, a field-programmable gate array (FPGA) or anapplication-specific IC (ASIC)), a hard disk, an HDD, a hybrid harddrive (HHD), an optical disc, an optical disc drive (ODD), amagneto-optical disc, a magneto-optical drive, a floppy disk, a floppydisk drive (FDD), magnetic tape, a holographic storage medium, asolid-state drive (SSD), a RAM-drive, a SECURE DIGITAL card, a SECUREDIGITAL drive, a flash memory card, a flash memory drive, or any othersuitable tangible computer-readable storage medium or a combination oftwo or more of these, where appropriate.

Particular embodiments may include one or more computer-readable storagemedia implementing any suitable storage. In particular embodiments, acomputer-readable storage medium implements one or more portions ofprocessor 608 (such as, for example, one or more internal registers orcaches), one or more portions of memory 620, one or more portions ofstorage 610, or a combination of these, where appropriate. In particularembodiments, a computer-readable storage medium implements RAM or ROM.In particular embodiments, a computer-readable storage medium implementsvolatile or persistent memory. In particular embodiments, one or morecomputer-readable storage media embody encoded software.

Herein, reference to encoded software may encompass one or moreapplications, bytecode, one or more computer programs, one or moreexecutables, one or more instructions, logic, machine code, one or morescripts, or source code, and vice versa, where appropriate, that havebeen stored or encoded in a computer-readable storage medium. Inparticular embodiments, encoded software includes one or moreapplication programming interfaces (APIs) stored or encoded in acomputer-readable storage medium. Particular embodiments may use anysuitable encoded software written or otherwise expressed in any suitableprogramming language or combination of programming languages stored orencoded in any suitable type or number of computer-readable storagemedia. In particular embodiments, encoded software may be expressed assource code or object code. In particular embodiments, encoded softwareis expressed in a higher-level programming language, such as, forexample, C, Perl, or a suitable extension thereof.

In particular embodiments, encoded software is expressed in alower-level programming language, such as assembly language (or machinecode). In particular embodiments, encoded software is expressed in JAVA.In particular embodiments, encoded software is expressed in Hyper TextMarkup Language (HTML), Extensible Markup Language (XML), or othersuitable markup language. The foregoing description of embodiments ofthe disclosure has been presented for purposes of illustration anddescription. It is not intended to be exhaustive or to limit thedisclosure to the precise form disclosed, and modifications andvariations are possible in light of the above teachings or may beacquired from practice of the disclosure. The embodiments were chosenand described in order to explain the principals of the disclosure andits practical application to enable one skilled in the art to utilizethe disclosure in various embodiments and with various modifications asare suited to the particular use contemplated. Other substitutions,modifications, changes and omissions may be made in the design,operating conditions and arrangement of the embodiments withoutdeparting from the scope of the present disclosure. Such modificationsand combinations of the illustrative embodiments as well as otherembodiments will be apparent to persons skilled in the art uponreference to the description. It is, therefore, intended that theappended claims encompass any such modifications or embodiments.

Depending on the embodiment, certain acts, events, or functions of anyof the algorithms described herein can be performed in a differentsequence, can be added, merged, or left out altogether (e.g., not alldescribed acts or events are necessary for the practice of thealgorithms). Moreover, in certain embodiments, acts or events can beperformed concurrently, e.g., through multi-threaded processing,interrupt processing, or multiple processors or processor cores or onother parallel architectures, rather than sequentially. Although certaincomputer-implemented tasks are described as being performed by aparticular entity, other embodiments are possible in which these tasksare performed by a different entity.

Conditional language used herein, such as, among others, “can,” “might,”“may,” “e.g.,” and the like, unless specifically stated otherwise, orotherwise understood within the context as used, is generally intendedto convey that certain embodiments include, while other embodiments donot include, certain features, elements and/or states. Thus, suchconditional language is not generally intended to imply that features,elements and/or states are in any way required for one or moreembodiments or that one or more embodiments necessarily include logicfor deciding, with or without author input or prompting, whether thesefeatures, elements and/or states are included or are to be performed inany particular embodiment.

While the above detailed description has shown, described, and pointedout novel features as applied to various embodiments, it will beunderstood that various omissions, substitutions, and changes in theform and details of the devices or algorithms illustrated can be madewithout departing from the spirit of the disclosure. As will berecognized, the processes described herein can be embodied within a formthat does not provide all of the features and benefits set forth herein,as some features can be used or practiced separately from others. Thescope of protection is defined by the appended claims rather than by theforegoing description. All changes which come within the meaning andrange of equivalency of the claims are to be embraced within theirscope.

What is claimed is:
 1. A method of monitoring force equalization (FEQ)sensors on a vehicle utilizing redundant actuation systems for one ormore control surfaces, the method comprising, by a computer system for avehicle: determining, via a force sensor, a first measured force appliedby a first actuation system in relation to a control surface, whereinthe control surface is redundantly serviced by a plurality of actuationsystems comprising the first actuation system; updating a measured-forcetime series for the first actuation system with the first measuredforce; determining variation in at least a portion of the measured-forcetime series responsive to the updating; and identifying a first staticcondition in the measured-force time series in response to adetermination that the variation in the measured-force time series is nogreater than a minimum amount of variation.
 2. The method of claim 1,wherein: the determining the variation comprises determining adifference between maximum and minimum values over an interval of themeasured-force time series; and the identifying the first staticcondition comprises: comparing the determined difference to the minimumamount of variation; and determining the first static condition to existresponsive to the determined difference being no greater than theminimum amount of variation.
 3. The method of claim 1, comprising:sending a command stimulus to at least the first actuation systemresponsive to the first static condition; and determining, via the forcesensor, new measured-force data comprising a second measured forceapplied by the first actuation system responsive to the sending of thecommand stimulus.
 4. The method of claim 3 comprising, responsive to adetermination that no static condition exists in the new measured-forcedata, treating the force sensor as responsive.
 5. The method of claim 3,wherein the sending comprises sending the command stimulus to each ofthe plurality of actuation systems in a sequential pattern.
 6. Themethod of claim 3, comprising: identifying a second static condition inthe new measured-force data; and classifying the force sensor asnon-responsive in response to the second static condition.
 7. The methodof claim 6, comprising executing FEQ failure logic in response to theclassifying the force sensor as non-responsive.
 8. The method of claim7, wherein the executing comprises disabling the first actuation system.9. The method of claim 2, wherein the force sensor comprises a deltapressure sensor.
 10. The method of claim 1, wherein the plurality ofactuation systems comprise a second actuation system and a thirdactuation system, and where the first, second, and third actuationsystems each comprise an actuator forming part of a common actuationcomponent.
 11. The method of claim 1, comprising: monitoring FEQcommands issued by the computer system to the first actuation system;and responsive to a determination that an FEQ command exceeds FEQauthority of the computer system, executing FEQ failure logic.
 12. Themethod of claim 1, wherein the vehicle is an aircraft.
 13. A vehiclecomputer system comprising a processor and memory, wherein the processorand the memory in combination are operable to perform a method ofmanaging force equalization (FEQ), the method comprising: determining,via a force sensor, a first measured force applied by a first actuationsystem in relation to a control surface, wherein the control surface isredundantly serviced by a plurality of actuation systems comprising thefirst actuation system; updating a measured-force time series for thefirst actuation system with the first measured force; determiningvariation in at least a portion of the measured-force time seriesresponsive to the updating; and identifying a first static condition inthe measured-force time series in response to a determination that thevariation in the measured-force time series is no greater than a minimumamount of variation.
 14. The vehicle computer system of claim 13,wherein: the determining the variation comprises determining adifference between maximum and minimum values over an interval of themeasured-force time series; and the identifying the first staticcondition comprises: comparing the determined difference to the minimumamount of variation; and determining the first static condition to existresponsive to the determined difference being no greater than theminimum amount of variation.
 15. The vehicle computer system of claim13, the method comprising: sending a command stimulus to at least thefirst actuation system responsive to the first static condition; anddetermining, via the force sensor, new measured-force data comprising asecond measured force applied by the first actuation system responsiveto the sending of the command stimulus.
 16. The vehicle computer systemof claim 15, the method comprising, responsive to a determination thatno static condition exists in the new measured-force data, treating theforce sensor as responsive.
 17. The vehicle computer system of claim 15,the method comprising: identifying a second static condition in the newmeasured-force data; and classifying the force sensor as non-responsivein response to the second static condition.
 18. The vehicle computersystem of claim 17, the method comprising executing FEQ failure logic inresponse to the classifying the force sensor as non-responsive.
 19. Thevehicle computer system of claim 13, wherein the vehicle computer systemcomprises a flight control computer.
 20. A computer-program productcomprising a non-transitory computer-usable medium havingcomputer-readable program code embodied therein, the computer-readableprogram code adapted to be executed to implement a method of managingforce equalization (FEQ), the method comprising: determining, via aforce sensor, a first measured force applied by a first actuation systemin relation to a control surface, wherein the control surface isredundantly serviced by a plurality of actuation systems comprising thefirst actuation system; updating a measured-force time series for thefirst actuation system with the first measured force; determiningvariation in at least a portion of the measured-force time seriesresponsive to the updating; and identifying a first static condition inthe measured-force time series in response to a determination that thevariation in the measured-force time series is no greater than a minimumamount of variation.